Rotary cutter for lawn-mowers.



No. 838,521. PATBNTED DEC. 1a, 1906.-

A. B. CASE.

ROTARY CUTTER FOR LAWN MOWERS.

APPLIUATION FILED SEPT.3,1904.

Z'7v /JJe -5: I EZ'flW/f ADELBERT B. CASE, OF SPRING-FIELD, MASSACHUSETTS.

ROTARY CUTTER FOR LAWN-IVIOWERS.

are. 838,521.

Specification of Letters Patent.

Patented Dec. 18, 1906.

Application file-i September 3, 1904. Serial No 223.213.

To 117/ 117mm, it may 00/1/6677):

Be it known that I, ADELBERT B. CASE, a citizen of the United States, residing at Springfield, in the county of Hampden and State of Massachusetts, have invented new and useful Improvements in Rotary Cutters for Lawn-Mowers, of which the following is a specification.

This invention relates to lawn-mowers, and has special reference to an improved construction of the blades of the rotary wiperknife.

The object of this invention is to provide a rotating cutter for lawn-mowers and the like in which the knife is better adapted to its work in connection with the stationary knife and in which the blades of the cutter are easily accessible for accurate sharpening.

The invention is clearly illustrated in the drawings forming a part of this application, in which Figure 1 is a sectional view of a lawnmower having wiper-blades embodying this invention applied thereto. Fig. 2 is a perspective view of a portion of a blade, showing the relation of a file thereto in the sharpening operation. Fig. 3 is a sectional view of a wiper-blade made according to this invention, showing its relation to the stationary knife. Fig. 4 is a similar view to Fig. 3, showing a wiper-blade and stationary knife and their relative positions as at present constructed.

Referring to the drawings, a is the frame of a lawn-mower, in which on a shaft 5 the Wiper- .blades 0 are supported in the usual manner on the spiders d, the blades being spirally disposed around said shaft. The stationary knife 6 is supported in the usual manner on a knife-barf, and preferably, though not necessarily, this knife is of that type in which the cutting edge is formed on a lip 9, turned up at an angle to the body, as shown in the drawings. The wiper-blades c are made from thin bar-steel, having one edge rolled down relatively thin, as at h, as shown in Fig. 4 but before bending the blades into spiral form this thin edge is bent backward relative to the face of the blade, as shown in Fig. 3 at j. The width of this bent-back marginal portion is relatively narrow and in practice need not exceed a quarter of an inch. The lower edge of the blade is beveled oif, as usual, to provide the proper clearance between the cutting edge thereof and the edge of the stationary knife 6. WVith the marginal portion of the cutting edge thus located at an angle relative to the face of the blade, as shown in said Fig. 3, it ispossible to apply a file to said portion of the blade at any part thereof and sharpen the cutting ed e without distorting said edge, whereas if the blade is made as shown in Fig. 4 it cannot be sharpened in thismanner without very great labor, owing to the extensive surface of the blade and owing to the fact that it is curved. Therefore it is customary to sharpen the blade as made at present by applying a file to the lower beveled edge m, and it is well nigh impossible to perform this operation by hand without producing an uneven cutting edge,

whereby certain parts of the blade will not touch the edge of the stationary knife 6 when the machine is in operation. Furthermore, with a blade made according to this invention the face of the turned-back marginal portion j is located more nearly at right an gles to the plane of the stationary knife 6 at the point of contact between the two, and the cutting edge of the blade therefore sweeps across the upturned lip of said stationary knife more nearly in a horizontal plane than is the case where the blade is made as in Fig. 4, in which construction the cuttin edge of the blade sweeps across the edge of said lip more diagonally. Therefore with the construction shown in Fig. 3 the machine may be adjusted so that the blades will bear more lightly on the stationary knife and do better work with less wear than is possible where the relation of the blade and the stationar knife is that shown in Fig. 4.

The face of the blade referred to herein refers to that surface facing the stationary knife 6 as the wiper-knife is rotated.

While the blade referred to herein is especially adapted to use on lawn-mowers, its use is not restricted to this class of machines, as it would be equally advantageous when embodied in any rotary cutter.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

1. In a lawn-mower, a fixed blade, a rotary knife having a spiral blade, the outer edge of which is thinner than the rest of the blade, the thin portion of the blade being bent back relatively to the direction of rotation so as to form a surface that stands at an angle to the body portion of the blade, said bent surface being substantially at a right angle to the fixed blade of the mower.

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2. In a lawn-mower, a fixed blade, a rotary stantially at a right angle to the fixed blade knlifehaving ta sgilral blaldler,l the outer margiof the mower When in engagement therewith. 11a ortion o W 'ch is t ner than the rest of the blade, the thinner portion being bent ADELBERCL CASE 5 back relative to the direction of rotation so as Witnesses:

form a surface that stands at an angle to the WM. H. CI-IAPIN, face of the blade, said bent surface being sub- 1' M. L. DONOVAN. 

